In the process of manufacturing many types of metals, particularly aluminum, the metal is formed in long sheets before being rolled into coils. In rolling the metal into a coil, a temporary mandrel is used on a coiling machine. Upon removal of the coil from the machine, its central aperture is normally unsupported while the coil rests on the floor with the aperture positioned along a horizontal axis. In order to produce desired properties in the metal, it is normally subjected to a heat treatment operation, such as annealing, wherein the malleability or strength of the metal is altered. One method of heat treatment requires the huge coils to be tipped on end such that the central aperture has a vertical axis. The coils are then stacked on a movable tray and transported into a furnace where they are left for a period of time. Another method of heat treating metal coils is to unwind each coil and insert a temporary spool. However, many manufacturers shy away from this process for it requires an extra operation which necessitates more time and added expense. In either case, it is desirable to avoid handling or rotating the coils for such handling can cause nicks, mars or scratches in the surface finish.
Up until now, manufacturers have been unable to place metal coils in a heat treatment furnace with their central apertures aligned in a horizontal plane, because the weight of the coils would tend to cause the configuration of the aperture to deform. Such deformation can prevent the coil from being processed downstream wherein a temporary spool has to be inserted into the aperture in order for the coil to be unwound. Some U.S. patents which disclose solutions to this problem include Nos. 3,948,595; 3,846,190; and 2,601,443. All three relate to a hollow temporary spool or spider arrangement which is designed to retain the shape of the internal diameter of the coil. However, all necessitate the unwinding of the coil in order to remove the temporary spool.
Now an apparatus and method have been invented which has the capability of being inserted into the internal diameter of a coil and expanded so as to retain the aperture's configuration during heat treatment. The apparatus is also able to retract and be removed without unwinding the coil.